Multicenter study of reference stabilized human blood for lymphocyte immunophenotyping quality control in flow cytometry. GEIL.

The development of automated methods and normative rules, as well as the dependence of some therapeutic approaches on lymphocyte subsets counts, has led to the appearance of calibration reagents. Such reagents are expected to perform equally well in very different settings. We developed a multicenter trial to evaluate the performance of a new quality control reagent, i.e., stabilized blood to be used in immunophenotyping laboratories. Aliquots of the same batch of stabilized blood were shipped to 45 French and Belgian laboratories on a Monday and had to be tested for percentages and absolute counts of at least CD3-, CD4-, and CD8-positive lymphocytes on 4 consecutive days. The percentages and absolute counts obtained on each assay were recorded, as well as the type of lysis used, the trademark of reagents, and the brand of flow cytometer. The mean values collected did not differ significantly from those expected by the manufacturer. Absolute counts generated through one-step techniques displayed lower CVs. This new reagent therefore appears to be a robust product, liable to yield consistent results in the array of different conditions represented by routine laboratories, and it could be useful for quality control procedures.